(1) Field of the Invention
The present invention relates to a touch panel which detects input coordinates in response to the change of resistance due to a push inputting manipulation and a screen input type liquid crystal display device constituted by laminating this touch panel thereto.
(2) Description of the Related Art
In a liquid crystal display device which is used as display means of a personal computer or a monitor of other device, an illumination light is irradiated to images formed on a liquid crystal panel and transmitting light or reflected light are irradiated to a display surface side so as to visualize the images.
In general, this type of liquid crystal display device uses a liquid crystal panel which inserts a liquid crystal layer into a gap defined between a pair of substrates having pixel selecting electrodes and the like at the time of laminating these substrates and forms images by changing the orientation state of liquid crystal molecules of selected pixel portions. Since the formed images per se are not in the visible state, light is given from outside and is irradiated to the liquid crystal panel and the transmitting light or the reflected light is observed.
Recently, information terminals which use this type of liquid crystal display device as display means have been widely used, wherein the information terminal is provided with a touch panel which is laminated to a screen of the liquid crystal display device (a display surface side of the liquid crystal panel which constitutes the liquid crystal display device) and inputs various information by a push manipulation through the screen.
Various types of touch panels exist in view of their operation principles and the most popular type is a type which detects input coordinates in response to a resistance change quantity, that is, a so-called analogue resistance film type.
The touch panel of this analogue resistance film type has one substrate which is disposed at an information input side constituted by a soft film such as a transparent plastic sheet and other substrate constituted by a transparent hard substrate preferably made of glass. The touch panel is further provided with resistance films on respective opposing surfaces of these two transparent substrates. In operation, a two-dimensional coordinates value is detected in response to resistance values between the resistance films of respective substrates which are brought into contact with each other by a push inputting manipulation applied from one substrate side and output terminals.
FIG. 13 is a schematic cross-sectional view which explains a schematic constitutional example of a screen input type liquid crystal display device which constitutes a liquid crystal display device provided with a touch panel. This screen input type liquid crystal display device is constituted by laminating a touch panel 4 to a liquid crystal panel 1. Although a light guide plate 2 which constitutes an auxiliary light source device 3 is inserted between the liquid crystal display device 1 and the touch panel 4, a screen input type liquid crystal display device which installs the auxiliary light source device 3 at the rear side of the liquid crystal display panel or a screen input type liquid crystal display device which has no auxiliary light source device 3 have been commercially available. In the drawing, numeral 3A indicates a lamp which constitutes the auxiliary light source device 3 and numeral 3B indicates a lamp reflection sheet which also constitutes the auxiliary light source device 3.
FIG. 14A and FIG. 14B are schematic cross-sectional views for explaining the constitution of an essential part of the touch panel and the state at the time of push inputting manipulation in FIG. 13. In the drawing, numeral 4A indicates an upper substrate made of a transparent film sheet and numeral 4B indicates a lower substrate made of a glass plate. On inner surfaces of these two substrates 4A and 4B, an upper resistance film 11 and a lower resistance film 12 are respectively formed by coating. Further, to an input region of the lower resistance film 12 formed on the lower substrate 4B, dot spacers 90 which prevent the upper and lower resistance films 11, 12 from coming into contact with each other in the non-inputting manipulation state are provided. These dot spacers 90 are formed by a printing by way of a mask having given apertures or a photolithography technique using photosensitive resin or other techniques.
The resistance films 11, 12 are respectively electrically connected with upper and lower wiring 55, 56 formed by printing on a seal region SL disposed at an outermost periphery of the touch panel. These upper wiring 55 and the lower wiring 56 are connected with a coordinates recognition circuit provided outside through lead wires not shown in the drawing.
The upper wiring 55 and the lower wiring 56 are respectively coated with protective films (insulation films) 71, 72 and these protective films 71, 72 are connected with each other by means of a sealing agent (adhesive agent or adhesive sheet) 80.
In the inside of the seal region SL, an input region AR is positioned by way of an inoperable region NR. The inoperable region NR is a portion which becomes insensitive at the time of push inputting manipulation. As shown in FIG. 14B, this inoperable region NR corresponds to an input invalid space which is generated when the upper substrate 4A is deflected toward the lower substrate 4B due to the pushing of a pen 560 which constitutes inputting means.
In general, to prevent the information inputting error at the time of push inputting manipulation with the pen 560, an inoperable region forming member 100xe2x80x2 is disposed in this inoperable region NR. That is, the inoperable region forming member 100xe2x80x2 is provided such that a tip of the pen surely enters the input region AR in the state shown in FIG. 14B.
However, with respect to the conventional touch panel having such a constitution, since a gap defined between the upper substrate 4A and the lower substrate 4B is large and the inoperable region forming member 100xe2x80x2 disposed in the inoperable region has a rectangular cross section, the upper substrate 4A is largely bent and deflected toward the lower substrate 4B due to the repeated push inputting manipulation of the pen 560. Accordingly, when the upper substrate 4A is deflected, a bending stress is concentrated on edge portions SF of the upper protective film 71 of the upper substrate 4A and the inoperable region forming member 100xe2x80x2.
As a result of repeated concentration of the bending stress, cracks CL occur on the upper resistance film 11 at the stress concentrated portions SF and hence, there have been problems such that it gives rise to an erroneous operation in coordinates detection or the upper substrate 4A per se suffers from damages thus giving rise to the failure in final products.
It is a first object of the present invention to provide a touch panel which can overcome the problems of the above-mentioned prior art and can prevent the upper resistance film 11 from the occurrence of cracks CL even when the push inputting manipulation is repeatedly performed and can obviate the erroneous operation in the coordinates detection, and to provide a screen input type liquid crystal display device having a high reliability which adopts such a touch panel.
To achieve the above-mentioned object, the touch panel of the present invention comprises:
an upper substrate having an upper resistance film formed on an inner surface of a soft film member,
a lower substrate having a lower resistance film formed on an inner surface of a hard plate,
a seal region for laminating the upper substrate and the lower substrate,
dot spacers disposed in a gap defined between opposing surfaces of the upper and lower resistance films,
an input region capable of obtaining a detection output which sets a contact position of the upper resistance film and the lower resistance film as a two-dimensional coordinates value when a push inputting manipulation is performed to push the upper substrate to the lower substrate side, and
an input inoperable region where the upper substrate is bent toward the lower substrate side due to the push inputting manipulation in a periphery of the input region and in the inside of the seal region, wherein
the touch panel further includes a stress attenuating member which gradually decreases a height thereof from the seal region side to the input region side in the input inoperable region.
Due to such a constitution, while having the function of the inoperable region forming member of the prior art which has been explained in view of FIG. 14A and FIG. 14B, the stress attenuating member also has a following function. That is, the inoperable forming member comes into contact with a plurality of points in the state that the upper substrate is deflected by the push inputting manipulation with a pen tip so that the bending stress of the upper substrate (also simply called xe2x80x9cstressxe2x80x9d hereinafter) can be dispersed to several portions thus attenuating the stress concentration. Accordingly, the occurrence of cracks onto the upper resistance film formed on the upper substrate or damages on the upper substrate per se which is derived from the repeated push inputting manipulation can be obviated.
Typical constitutions provided to the above-mentioned touch panel are as follows. That is,
1) The upper resistance film and the lower resistance film are both constituted by a planar or flattened resistance film (uniform film).
2) Either one or both of the upper resistance film and the lower resistance film are made of a large number of comb-shaped resist films having one ends thereof formed into a common connection portion. When both resistance films have the comb-shaped resistance films, they are arranged in an intersecting manner from each other.
3) The stress attenuating member is formed of a material equal to a material of the dot spacers which are provided for forming a gap between opposing surfaces of the upper and lower substrates to prevent the constant contact of the resistance films formed on the upper and lower substrates.
4) The stress attenuating member is constituted by a set made of a plurality of independent members whose heights are decreased from an outer peripheral side of the touch panel, that is, the seal region side to the input region side. These independent members may have any one of a conical cross section, a cylindrical cross section, an elliptic-conical cross section or a polygonal cross section including a triangular cross section. These independent members may have their cross-sectional area decreased corresponding to the decrease of their heights.
5) The stress attenuating member is constituted by a plurality of continuous wall members whose heights are decreased from the seal region side to the input region side of the touch panel and these wall members are arranged concentrically about the center of the input region. These continuous wall members are formed in a bank shape which surrounds the input region and may have any one of a conical cross section, a cylindrical cross section, an elliptic-conical cross section or a polygonal cross section including a triangular cross section. These continuous wall members may have their cross-sectional area decreased corresponding to the decrease of their height.
6) The stress attenuating member is formed on the lower substrate side. Although a similar effect can be obtained by forming the stress attenuating member on the upper substrate side, by simultaneously forming the stress attenuating member at the time of forming the dot spacers or the protective film (insulation film) on the lower substrate, it is unnecessary to increase the fabrication steps.
7) To the upper substrate or the lower substrate, a lower resistance film connection portion or an upper resistance film connection portion which is electrically connected with the common connection portion of the lower substrate or the upper substrate is provided.
8) The upper resistance film and the lower resistance film are formed into a shape made of a large number of thin comb-like resistance films which are provided with a common connection portion at one ends thereof. Due to such shape made of thin comb-like resistance film, the resistance control of respective resistance films can be facilitated.
9) The upper resistance film member is formed into a shape made of a large number of thin comb-like resistance films which are provided with a common connection portion at one ends thereof and the lower resistance film is formed into a uniform resistance film. Due to such shape made of thin comb-like resistance film, the resistance control of upper resistance film can be facilitated.
A screen input type liquid crystal display device adopting the above-mentioned touch panel comprises:
a liquid crystal panel sandwiching a liquid crystal layer between a pair of substrates, and
the touch panel laminated to a screen of the above-mentioned liquid crystal panel, wherein the touch panel comprises:
an upper substrate having an upper resistance film formed on an inner surface of a soft film member,
a lower substrate having a lower resistance film formed on an inner surface of a hard plate,
a seal region for laminating the upper substrate and the lower substrate,
dot spacers disposed in a gap defined between opposing surfaces of the upper and lower resistance films,
an input region capable of obtaining a detection output which sets a contact position of the upper resistance film and the lower resistance film as a two-dimensional coordinates value when a push inputting manipulation is performed to push the upper substrate to the lower substrate, and
an input inoperable region where the upper substrate is bent toward the lower substrate side due to the push inputting manipulation in a periphery of the input region and in the inside of the seal region, and
the touch panel further including a stress attenuating member which gradually decreases a height thereof from the seal region side to the input region side in the input inoperable region.
Due to such a constitution, while ensuring the function of the inoperable region forming member of the prior art, the stress attenuating member provided to the touch panel also has a function of dispersing the bending stress of the upper substrate which is generated in the state that the upper substrate is deflected due to the push inputting manipulation with a pen tip thus attenuating the concentration of the bending stress. Accordingly, the occurrence of cracks onto the upper resistance film formed on the upper substrate or the damages on the upper substrate per se can be obviated so that the erroneous operation of the coordinates inputted to the screen can be prevented thus providing a screen input type liquid crystal display device having a high reliability.
Typical constitutions provided to the touch panel which constitutes the above-mentioned screen input type liquid crystal display device are as follows. That is,
1) The upper resistance film and the lower resistance film are both constituted by a planar or flattened resistance film (uniform film).
2) Either one or both of the upper resistance film and the lower resistance film are made of a large number of comb-shaped thin resist films having one ends thereof formed into a common connection portion. The upper resistance film and the lower resistance film have their comb-shaped thin resistance films to intersect with each other.
3) The stress attenuating member is made of a material which is equal to a material of the dot spacers for defining the gap between the upper and lower substrates or a protective film (insulation film) for coating a wiring.
4) The stress attenuating member is constituted by a set made of a plurality of independent members whose heights are decreased from the seal region side to the input region side.
5) The stress attenuating member is constituted by a plurality of parallel continuous wall members whose heights are decreased from the seal region side to the input region side of the touch panel and these wall members are arranged concentrically about the center of the input region.
6) The stress attenuating member is formed on the lower substrate side.
7) To the upper substrate or the lower substrate, a lower resistance film connection portion or an upper resistance film connection portion which is electrically connected with the common connection portion of the lower substrate or the upper substrate is provided.
8) The upper resistance film is formed into a shape made of a large number of thin comb-like resistance films which are provided with a common connection portion at one ends thereof and the lower resistance film is formed into a uniform resistance film.
9) An auxiliary light source device having a light guide plate and a linear lamp is disposed between the liquid crystal panel and the touch panel.
10) An auxiliary light source device having a light guide plate and a linear lamp is disposed at a back surface of the liquid crystal panel.
11) An auxiliary light source similar to the above-mentioned device is provided to the touch panel side or a linear or spot light source is provided to one side periphery of the touch panel.
As the liquid crystal panel used in the screen input type liquid crystal display device, a so-called simple-matrix type panel, an active-matrix liquid crystal type panel, or a liquid crystal panel of known type can be used. Further, the liquid crystal display device is applicable not only to a reflection-type liquid crystal display device but also to a transmission-type liquid crystal display device.
The present invention is not limited to the above-mentioned constitutions and the constitutions of embodiment which will be explained later and is applicable to a touch panel of a type which detects coordinates in response to the change of capacity or the change of other quantity of electricity between the upper substrate and the lower substrate or a digital type touch panel in the same manner, and various modification can be considered without departing from the technical concept of the present invention.
According to the present invention, it becomes possible to provide a touch panel which can prevent the occurrence of damages such as cracks on the upper resistance film or the upper substrate even when the push inputting operation is repeatedly performed and can eliminate the erroneous operation in detection of coordinates and a screen input type liquid crystal display device having a high reliability using such a touch panel.